As a method for forming a high-quality semiconductor film, there is an epitaxial growth technique which grows a single-crystal film on a substrate, such as a wafer, using vapor phase growth. In a vapor phase growth apparatus using the epitaxial growth technique, a wafer is placed on a support portion in a reactor which is maintained at normal pressure or reduced pressure. Then, process gas, such as source gas which will be a raw material for forming a film, is supplied from an upper part of the reactor to the surface of the wafer in the reactor while the wafer is being heated. For example, the thermal reaction of the source gas occurs in the surface of the wafer and an epitaxial single-crystal film is formed on the surface of the wafer.
In recent years, as a material forming alight emitting device or a power device, a gallium nitride (GaN)-based semiconductor device has drawn attention. Metal organic chemical vapor deposition (MOCVD) method is an epitaxial growth technique that can form a GaN-based semiconductor film. In the organic metal vapor phase growth method, organic metal, such as trimethylgallium (TMG), trimethylindium (TMI), or trimethylaluminum (TMA), or ammonia (NH3) is used as the source gas.
JP H10-158843A and JP 2002-212735A disclose a vapor phase growth apparatus that includes a plurality of reactors in order to improve productivity. In addition, JP 2003-49278A discloses a method that changes the pressure control value of a reactor caused a trouble when films are grown in a plurality of reactors.